Pollution monitoring, and fire protection and suppressant systems may operate by detecting the presence of smoke and other airborne pollutants. Upon a threshold level of particles being detected, an alarm or other signal may be activated and operation of a fire suppressant system and/or manual intervention may be initiated.
Air sampling pollution monitoring equipment in the form of aspirated particle detection systems may incorporate a sampling pipe network consisting of one or more sampling pipes with one or more sampling holes, or inlets, installed at positions where smoke or pre-fire emissions may be collected from a region or environment being monitored, which is ordinarily external to the sampling pipe network. Typical configurations for aspirated particle detection systems are shown in FIGS. 1 and 2 in the form of aspirated smoke detection systems 10 and 20, respectively. Air is drawn in through the sampling holes 14, 24 and subsequently along the pipe or pipe network 12, 22 by means of an aspirator or fan (not shown) and is directed through a detector 16 at a remote location. Sampling points in the form of the sampling inlets 14, 24 are located at regions where particle detection is required. These regions are typically distant from the actual detector. Although there are a number of different types of particle detectors which may be used as the detector in a system as outlined above, one particularly suitable form of detector for use in such a system is an optical scatter detector, which is able to provide suitable sensitivity at reasonable cost. An example of such a device is a VESDA® LaserPlus™ smoke detector as sold by the applicant.
Optical scatter detectors operate on the principle that smoke particles or other airborne pollutants of small size, when introduced into a detection chamber and subjected to a high intensity light beam, will cause light to scatter. A light detector senses the scattered light. The greater the amount of particles within the sample introduced into the detector chamber the greater will be the amount of light scatter. The scatter detector detects the amount of scattered light and hence is able to provide an output signal indicative of the amount of smoke particles or other pollutant particles within the sample flow.
When aspirated particle detector systems are installed in environments that are subject to varying environmental conditions it would be beneficial to be able to not only detect the level of pollutants or smoke particles in the environment being monitored, but also to be able to monitor the level of heat in the environment, irrespective of the level of particles. It would be particularly beneficial to be able to monitor both the level of particles and heat in the environment since a high level of each in combination is generally indicative of fire.
Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.